Peter Herzog's energy management book summary 1213

Hello,

I teach state-of-the-art existing buildings operations and maintenance (EBOM) and energy management courses for some of the foremost training institutions in New York City. A substantial part of the energy management teaching is based on Peter Herzog’s book: “Energy-Efficient Operation of Commercial Buildings” which is also a course handout.

Written some years ago, in my opinion this is still the very best practical guide on the implementation of energy management in commercial (and multifamily) buildings, and is very well received by my students.

Mr. Herzog has authorized the publication and free use of this presentation for non-profit, educational purposes, as long as the content is not altered in any way.

Mr. Herzog’s book can be found here: http://www.nweei.org/commercial-efficiency-text-in-print.html

Moreno Tagliapietra, 914-712-0823, [email protected] – January 2014

http://www.nweei.org/commercial-efficiency-text-in-print.html

mailto:[email protected]

Herzog:“Energy-Efficient Operation

of Commercial Buildings”

A summary by Moreno Tagliapietra – December 2013

Scope and Purpose

This presentation is a summary of the principles, tools and techniques expounded by Peter Herzog in his book “Energy-Efficient Operation of Commercial Buildings”

It is intended to be used as a review of the book’s key points after its content has been exhaustively studied

Herzog: “Energy-Efficient Operation of Commercial Buildings” – Summary by Moreno Tagliapietra – Dec 2013

Herzog’s Building Energy Efficiency Model

Major loadsIdentified

Prioritizationof ongoingactivities


Herzog’s Building Energy Efficiency ModelEnergy Use Allocation Methods


1. Top-down allocation:

Beginning from the aggregated energy consumption shown in the utility bills, systems demand and operating hours are estimated and used to disperse the total use among the different systems (consuming the same type of energy)

This method has poor precision but is accurate enough to identify a building’s major loads and prioritize energy conservation measures

It also provides for final verification of the accuracy of the equipment/system level allocation methods: the disaggregated figures must sum up to the totals shown in the utility bills



2. Bottom-up, take-off method:

• This method works at the equipment/system level

• Manufacturer’s specs and name plate data are used to estimate equipment/system demand

• Hours of operation are estimated as in the previous method

• Precision and accuracy are better than with the top-down method because variables such as input/output full-load rates and efficiency are known but others are still estimated including partial/variable load factors and firing rates, and schedule



2. Bottom-up, measurement method:

Instrumentation is used, most often in conjunction with data loggers, to test/measure the actual energy use of individual pieces of equipment or whole systems

Tests and measurements are conducted for a period of time representative of all possible working conditions

This method affords the highest level of confidence in terms of precision and accuracy of energy use allocation

3 Tenets: • Efficient purchasing• Efficient operation• Efficient equipment

Benefits: • Substantial energy and cost savings• Low implementation costs• Higher comfort and productivity• Better info for capital improvement decisions

Achieving Energy Efficiency Through O&M


Barriers: • Potential savings not understood by management• Maintenance procedures not designed for operating efficiency• Focus on engineering rather than on management processes• Management structure inhibits operating efficiency• No available methods for managing operating efficiency



The process, overview:

• Identify the types of energy consumed by the building• Identify the equipment consuming the energy• Estimate the energy consumption of the equipment (from the bills)• Determine the true energy demand• Measure the true consumption• Optimize O&M to minimize the difference between the two



The Role of Management:• Value energy-efficient operation• Develop enthusiastic participation• Recognize cross-functional nature of effort• Define return on investment• Institute methods of accounting• Designate a start-up leader• Recognize needs during start-up phase



Start-up activities:• Create an energy management file• List energy consuming devices and systems• Collect drawings and specifications• Tour building to trace energy flow paths• Draw schematic diagrams



Page 38 Figure 3-12

Electrical RiserDiagram


Page 48 Figure 3-123

Schematic ofAir HandlingUnit


Achieving Energy Efficiency Through O&M Estimating Electricity Use

Constant electricity users:

•Lighting

•Constant rate electric motors

•Variable rate electric motors

•Two-speed motors

•Office equipment

•Electric water heaters

•Miscellaneous equipment

Weather-variable electricity users:

•Electric heating

•Electric cooling

•Electric heat pumps


Estimating electricity use:

• Assemble utility bills information• Gather information on operating schedules• Estimate annual use of electric equipment• Allocate total annual electrical energy cost



Page 53, Figure 4.3 Electrical use for example office building


Page 56, Figure 4.5Graphing electric bills data


Page 58, Figure 4.7 - Operating schedule


Page 62, Figure 4.10Allocation of annual electrical energy cost


Estimating natural gas use: the process is the same as per electricity

Page 69, Figure 5-4 – Combined natural gas & oil


Page 70, Figure 5-5 – Natural gas AVG daily use x month



Page 76, Figure 6-1Ongoing activities

M&V,new baseline


From set-up to on-going activities:• The most useful outcome of the set-up activities is to identify the

building’s major loads so that the on-going activities can be prioritized

• At this stage, it is key for the energy management team to secure the participation and cooperation of everyone who influences how and when systems are operated

• The final goal here is to ensure that equipment is running only when necessary and that only the required amount of energy is consumed



Step 4: Measure actual energy use• Decide what to measure Energy consumption, rate over time Fixed vs variable rates• Decide how to measure and with what instruments Utility meters, aggregate consumption Individual equipment measurementso Temperatureo Humidityo Pressureo Flowo Electrical current• Data loggers



Step 5: Determine required energy use

• The energy management team finds out what the actual, often variable building loads are and, consequently, what the actual systems set points and hours of operation should be

• It is common to discover that many building systems either operate when there is no need or that their schedule is out of synch with the current space occupancy schedule



Page 89, Figure 6-8 – Required vs. real use graph



Step 6: Minimize the difference between actual and required energy use

• Estimate savings potential

• Explore all the EEM(s) that would achieve these savings and select the ones with the highest ROI

• Implement the EEM(s), measure and verify the results (M&V program)



Example # 1: Lighting, office building• Draw an electrical riser diagram• Measure light intensity with a light meter• Measure actual lighting use with clamp amp-meters at the distribution

panel feeders, connected to a data logger• Determine the required lighting schedule• Adjust lamp wattage for the light level recommended by IESNA • Adjust actual to required lighting use with the adoption of automatic

controls (occupancy and vacancy sensors, timers, multi-level switches, digital controllers, daylight harvesting, zoning (common areas vs. task), dimming/trimming)

• Upgrade light fixtures and lamps• Take into consideration the code LPD requirements



Page 112, Figure 7-12 – Actual vs. required energy use profile



Basic lighting calculations (annual, fluorescent, take off method):

Demand, kW = (Watts/lamp x # lamps/fixture x # fixtures x 1.1 ballast) / 1000

Schedule, Hours = op hours/day x days/week x weeks/year

Use, kWh = demand kW x schedule hours

Cost = use kWh x $/kWh

Note: Lighting is a fixed load unless operator’s dimming is used



Lighting power measurements (pg 154):



Lighting power measurements (pg 154):



Example # 2: roof top Air Handling Units,

ventilation + cooling, office building:

• Identify energy consuming devices (compressor + fans)

• Draw a diagram of the AHU system with distribution

• Identify the unit sequence of operations: Programmed daily schedule with room thermostat over-run Supply air temp = 55dF, VAV boxes Perimeter radiators, room thermostat driving VAV boxes as well

(prevents simultaneous heating + cooling) Economizer Supply fan with modulating inlet vanes, pressure sensor in

supply air DX cooling system with sensor in supply air (55dF)




ventilation + cooling, office building

Goals:

• The fans operating schedule must match as closely as possible the needs of the building occupants

• The mixed air economizer control must function as intended

• The supply air temperature must be maintained at the highest acceptable value

• Unnecessary simultaneous heating and cooling must be avoided at the perimeter spaces




ventilation + cooling, office building

What to measure (key operating variables):

• Fan on/off schedule

• Mixed air temperature in economizer mode

• Supply air temperature

• Possibility of simultaneous heating and cooling of perimeter spaces



Example # 2: roof top Air Handling Units, ventilation + cooling, office building

Where to measure:


AHUPage128



Page 128 - Figure 8-13 – AHU measurements findings



Energy management team conclusions:

The AHU required operating hours are found to be 65/week The AHU actual operating hours are 122/week or + 57 hours/week The AHU operates 52 weeks/year (ventilation!) Reducing the operating hours of the 3 phase fan would save: (30A x 460V x 1.73 x 57h/week x 52weeks/year x 0.18$/kWh) / 1000 =

= $ 12,737/year

The compressor savings are difficult to calculate and are estimated to be about 20% of the original cooling costs based on known operating conditions


Motors, page 157:


Motors, pg 157:


Motors

Page 161, Figure A-2:


Electric water heating, Pg 168:


Electric heating & cooling, Pg 168:


Miscellaneous electrical uses, Pg 169:

“Usually there [is] a number of electricity-consuming devices that are too small to be itemized in this general allocation, but their aggregated energy use may account for 5% to 15% of the total annual consumption.

Examples include pneumatic control air compressors, small circulating pumps and exterior building lighting.

Account for miscellaneous electrical users by assuming they consume 10% of the annual total kWh.”


Estimating constant fuel consumers, Pg 183:


The end, any

questions?Herzog: “Energy-Efficient Operation of Commercial Buildings” – Summary by Moreno Tagliapietra – Dec 2013

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Peter Herzog's energy management book summary 1213